This invention relates generally to turf conditioning apparatus and more particularly to a light-weight, computer controlled liquid injection system for conditioning golf greens.
Golf greens on golf courses must be meticulously cared for to remain in proper condition for playing golf. For example, if the golf green is too dry or becomes too compacted, the ground becomes too hard and the golf ball will not properly bounce or "bite" on the golf green. If there is heavy traffic on the golf green, part of the green becomes compact, creating an uneven putting surface. Extensive use of a golf green also results in severe turf wear. Extensive soil compaction reduces water infiltration into the soil, percolation and drainage out of the soil and tends to restrict and reduce root growth.
Many turf aeration systems have been developed that cultivate the ground to increase water drainage and spur proper root growth. One method presently used for conditioning soil consists of directing fluid at high pressure into the ground to breakup or cultivate the soil.
For example, U.S. Pat. No. 5,119,744 to Comer shows a hydraulic aeration system that lifts and fractures the subsurface soil to decrease soil density. The system in Comer provides individual high-pressure jets of fluid that are output from corresponding nozzles. Each nozzle generates a conical fluid dispersion pattern that is directed laterally from the direction of fluid penetration into the ground. The distance between each nozzle and the speed in which the machine is propelled over the ground cause the dispersion patterns of adjacent nozzle jets to coact lifting and fracturing the soil to reduce soil density.
The system shown in Comer, however, is a general purpose turf conditioning system and is not capable of meeting the meticulous conditioning requirements of golf greens. For example, the wide laterally extending fluid dispersion pattern in Comer forms large conically shaped holes underneath the ground. The large amount of soil displacement created by each nozzle is problematic since spray from adjacent nozzles overlap. Thus, the entire soil substructure is disrupted. Large overlapping holes are created underneath the turf surface which are susceptible to "cave-ins". Thus, if too much pressure is exerted on the top of the golf green after the Comer aeration process has been performed, the top surface of the green can actually cave-in forming divots.
In addition, Comer disperses the same depth and the same pattern of fluid into the ground regardless of turf conditions. A more compact soil; a harder soil, such as clay; or a drier soil requires more fluid pressure or a longer fluid dispersion time to drill a given distance into the ground than softer soil conditions. However, if the fluid pressure is too high or if the nozzles are kept on too long, the aeration system will displace too much soil severely damaging the golf green.
The system disclosed in Comer is also heavy and actually compacts the soil as it travels over the golf green. For example, the system in Comer contains a water accumulator, a large engine and a pump. The weight of all this equipment negates some beneficial effects of aeration by further compressing the soil. For sensitive turf surfaces, such as golf greens, even lightweight machinery is prohibited. The system in Comer creates depressions or ruts in the turf surface, actually degrading rather than opposed to improving golf green conditions.
U.S. Pat. No. 4,009,666 to Russell et al. discloses an apparatus for injecting liquid below the surface of turf. Russell et al., applies a continuous stream of liquid into the turf rather than periodic slugs, or jets, of pressurized liquid. A continuous stream creates continuous cuts in the top surface of the ground which often are not desirable for golf green preparation. In addition, the system in Russell et al. maintains the same fluid pressure independently of soil conditions. Thus, the depth of each cut may be either too deep or too shallow.
U.S. Pat. No. 4,907,516 to Rogers shows a tractor that injects fertilizer and other liquid crop treatments into the ground by directing injection jets with a nozzle. A solenoid controlled valve generates short pulses of fluid that penetrate 2 to 4 inches into the ground. The system in Rogers, however, is used for inserting fertilizer and is not designed for the precise conditioning requirements of a golf green. For example, the tractor in Rogers is too heavy and would severely compress the soil when traveling over a golf green. Thus, the system would worsen turf conditions by placing ruts in the golf green. In addition, Rogers as in Russell et al. and Comer, does not vary the amount of fluid dispersion according to present turf conditions.
Accordingly, a need remains for a light-weight golf green conditioning system that is adaptable to different turf conditions.